The invention relates to "effect" pigments based on interference pigments coated with phthalocyanine or metal phthalocyanine dyes, the dyes being applied to the pigments as a strongly adhering film without auxiliary materials. Interference pigments owe their color to the interference effects of light passing through a translucent coating onto an opaque substrate such as a flaky mica, whereas "effect" pigments are those whose color is due both to absorption and interference effects.
Various processes are known for dyeing pigments with organic dyes, for example, simple mixing of pigment and dye (U.S. Pat. No. 4,755,229), suspending the pigment in dye solution (U.S. Pat. No. 3,311,485), grafting (EP 0,103,986) and adhesion with the aid of a binder system (EP 0,220,617).
In particular, a permanent coating with phthalocyanine dyes, has hitherto been achieved exclusively with the aid of binders, for example, polymers as described, for example, in the laid-open specifications EP 220,617 and JP 59/47,240, and in U.S. Pat. No. 4,755,229, or with coprecipitation of metal hydroxides, as described in Czechoslovakian Patent CZ 244,792.